Switching to function quick sort version

scala/official-by-example/byx/src/main/scala/sort.scala

@@ -1,23 +1,12 @@
 object sort {
-  def sort(xs: Array[Int]) {
-    def swap(i: Int, j: Int) {
-      val t = xs(i); xs(i) = xs(j); xs(j) = t
-    }
-    def sort1(l: Int, r: Int) {
-      val pivot = xs((l + r) / 2)
-      var i = l; var j = r
-      while (i <= j) {
-        while (xs(i) < pivot) i += 1
-        while (xs(j) > pivot) j -= 1
-        if (i <= j) {
-          swap(i, j)
-          i += 1
-          j -= 1
+  def sort(xs: Array[Int]): Array[Int] = {
+    if (xs.length <= 1) xs
+    else {
+      val pivot = xs(xs.length / 2)
+      Array.concat(
+        sort(xs filter (pivot >)),
+             xs filter (pivot ==),
+        sort(xs filter (pivot <)))
     }
   }
-      if (l < j) sort1(l, j)
-      if (j < r) sort1(i, r)
-    }
-    sort1(0, xs.length - 1)
-  }
 }